Fundamental interactions experiments with polarized trapped nuclei

Transcription

1 Fundamental interactions experiments with polarized trapped nuclei β + DESIR meeting Leuven, May 2010 ν e Nathal Severijns Kath. University Leuven, Belgium 5/31/2010 N. Severijns, DESIR Workshop - Leuven - May 26-28,

2 1. searches for exotic weak currents (non V-A) - tensor currents - scalar currents 2. symmetry tests - parity - time reversal / CP violation 3. determine V ud and test CVC 5/31/2010 N. Severijns, DESIR Workshop - Leuven - May 26-28,

3 distribution in - electron and neutrino directions and in - electron energy from polarized nuclei : Correlation measurements r ω ( J E, Ω, Ω ) de dω dω e e ν e e 2 e e e 0 e Ee d e F( ± Z, E ) p E ( E E ) d Ω dω Fermi function ν phase space ν I θ β r r J p A J E e e r r pe q a E Eν e e + θ ν e r r r r r r pe q γ me J pe J p x ξ 1 + a + b + A + R σ x EeEν E e J Ee J nucleus β-ν correlation Fierz interference term ( b 0 in standard model ) J,D, Jackson, S.B. Treiman, H.W. Wyld, Nucl. Phys. 4 (1957) 206 β-asymmetry /31/2010 N. Severijns, DESIR Workshop - Leuven - May 26-28, X% = e E e R-correlation X γ m e 1 + b Ee

4 114 In and 60 Co beta asymmetry parameter, A Wauters et al. in 13 T external polarizing field; used GEANT4 code to account for : - detection geometry - magnetic field effects - scattering Si p-i-n diode (500 µm, = 9 mm) operating at 10 K Leuven 3 He - 4 He dilution refrigerator setup 5/31/2010 N. Severijns, DESIR Workshop - Leuven - May 26-28,

5 region analysed N(θ) pol v W(θ) = = 1 + A % P Q cosθ N(θ) c unpol (P from anisotropy of γ-rays ) Geant 4 Analysis of measured and simulated spectra: performance of GEANT simulation code -- F. Wauters, NS et al., submitted to NIM A no energy dependence left corrections OK [ ] [ W(θ) 1] v A % P Q cosθ = v Geant A % P Q cosθ SM c exp W(θ) 1 exp c exp Geant A exp ( 60 Co) = (12) stat (16) syst ( A SM = (9) ) F. Wauters et al., submitted 5/31/2010 5

6 A exp ( 114 In) = (10) stat (10) syst (A SM = ) (most precise result for A nuclear ever! ) F. Wauters et al., Phys. Rev. C 80 (2009) (R) major systematic errors: - performance of GEANT code (scattering) - determination of nuclear polarization ( 67 Cu in progress) (M)LRS-models 114 In W 1 = W L cosζ - W R sinζ W 2 = W L sinζ + W R cosζ this work 60 Co δ = m 1 2 / m In : M(W 2 ) > 230 GeV/c 2 (90% C.L.) 60 Co : M(W 2 ) > 245 GeV/c 2 (90% C.L.) 5/31/2010 N. Severijns, DESIR Workshop - Leuven - May 26-28,

7 Polarizing atoms/ions in a particle trap: - Paul trap : optical pumping of ion cloud (LPC-GANIL) in magnetic holding field - Penning trap : collinear polarization by optical pumping (WITCH-ISOLDE, DESIR) in beam line before trap - MOT trap : optical pumping of ion cloud (TRIUMF, Berkeley, KVI) in magnetic holding field Alternative : stop ions in superfluid He and polarize by optical pumping (cf. talk by T. Shimoda) 5/31/2010 N. Severijns, DESIR Workshop - Leuven - May 26-28,

8 Example of polarized atoms in MOT: neutrino asymmetry parameter for 37 K B 37 ν ( K) = 0.755(24) B SM ν = 0.779(6) 5 % precision very difficult to determine nuclear polarization precisely! TRINAT MOT TRIUMF M W 2 > 180 GeV/c 2 (90 % C.L.) 37 K D. Melconian, J.A. Behr et al., Phys. Lett. B 649 (2007) 370 5/31/2010 N. Severijns, DESIR Workshop - Leuven - May 26-28,

9 Polarization by optical pumping and determination of nuclear polarization via photoionization in a MOT 37 K D. Melconian, J.A. Behr et al., Phys. Lett. B 649 (2007) Rb J.R.A. Pitcairn, J.A. Behr et al., Phys. Rev. C79 (2009) /31/2010 N. Severijns, DESIR Workshop - Leuven - May 26-28,

10 Longitudinal polarization of positrons emitted by polarized nuclei with : P - (P + ) is β particle longitudinal polarization for β s emitted opposite to (in the direction of) the polarized nuclear spin vector (P 0 for unpolarized nuclei) (M)LRS-models W 1 = W L cosζ - W R sinζ W 2 = W L sinζ + W R cosζ 5/31/2010 δ = (M W1 ) 2 / (M W2 ) 2 10 N. Severijns, DESIR Workshop - Leuven - May 26-28, 2010

11 Results : signal M W 2 > 320 GeV/c 2 (90 % C.L.) 1) N. Severijns et al., PRL 70 (1993) 4047, 73 (1994) 611 2) M. Allet et al., Phys. Lett. B363 (1996) 139 3) E. Thomas et al., Nucl. Phys. A694 (2001) 559 4) N. Severijns et al., Nucl. Phys. A629 (1998) 423c 5/31/2010 N. Severijns, DESIR Workshop - Leuven - May 26-28,

12 /31/2010 N. Severijns, DESIR Workshop - Leuven - May 26-28,

13 3. Relative positron polarization measurements with polarized nuclei _ 2 2 8β A β A exp 2 exp 1 Aexp ( δ ζ ) with β 2 exp β + exp 1 exp P R = R + R = + P A A A sensitivity factor k (>> for β 2 = A exp!) A exp P A cos = β θ β = v/c ; P = nuclear polarization Isotope k sensitivity to M W2 [GeV/c 2 ] (90% C.L.) 17 F Na Al Sc N In significant potential compared to present lower limit of 320 GeV/c 2 ( for P = 0.80, and a 1% precision on R/R 0 ) 5/31/2010 N. Severijns, DESIR Workshop - Leuven - May 26-28,

14 T = 1/2 superallowed mirror transitions with ρ = C A M GT / C V M F mirror f A Ft0 = Ft 1+ ρ = 2Ft fv = G + + V K (1 + ) 2 2 V F ud R accuracy of 0.1 % to 0.4 % for most cases [ NS, I.S. Towner et al., Phys. Rev. 78 (2008) ] 5/31/2010 N. Severijns, DESIR Workshop - Leuven - May 26-28, 2010

15 - extract mixing ratio ρ =CAMGT / CV MF from correlation measurements: - there are 35 candidates between 3 H and 83 Mo, near the N = Z line (best are the ones with A < 45 about) - correlation measurements have been carried out for: 17 F, 19 Ne, 21 Na, 29 P, 35 Ar and 37 K 5/31/2010 N. Severijns, DESIR Workshop - Leuven - May 26-28,

16 [ O. Naviliat-Cuncic & N.S., Phys. Rev. Lett. 102 (2009) reduce by new measurements of Ft values and correlation coefficients 5/31/

17 - sensitivity of a and A for mirror nuclei, best cases : requires δ(ft )~ 5 x 10-4 i.e. factor 2-10 better Note: - V ud from a βν βν for all mirror transitions up to 39 Ca if no error from Ft - V ud ( ) = ± and V ud (mirror) = ± /31/2010 N. Severijns, DESIR Workshop - Leuven - May 26-28,

18 B. Time reversal 1. D triple correlation 2. R triple correlation this is for another talk. 5/31/2010 N. Severijns, DESIR Workshop - Leuven - May 26-28,

19 relative contributions to error bars of Ft values for mirror nuclei half-life Q value branching 5/31/ N.

20 Complimentarity of beta decay RHC results and collider results, in general LRS models PDG (CDF exp.) PDG (D0 exp.) 5/31/2010 κ RL = g R / g L shaded areas are excluded N. Severijns, DESIR Workshop - Leuven - May 26-28, 2010 λ RL = V ud R / V ud L 20